Radiation therapy using proton and ion beams is an effective method to treat various types of localized malignant tumors [1]. One of the main issues of using radiation for treatment is the lack of the capability to determine the dose deposited in organs in real time during the treatment. This is important to guide the treatment, to adjust the ion beam in real time so that minimal dose is delivered to sensitive organs and noncancerous tissue, to correct for the movement of the organs inside the body, and to act as a fail-safe mechanism. Over the past years, there have been several accidents with radiation treatment procedures which led to deliveries of much higher doses than planned, or radiation delivered to wrong areas, leading to fatalities. Mapping the radiation dose delivered during a treatment session is also important for the planning of future treatment sessions.